Oligosaccharide propionate compositions and processes



United States Patent US. Cl. 260-227 2 Claims ABSTRACT OF THE DISCLOSUREoligosaccharide propionates having an average degree of polymerizationof from about 4 to about 20 and containing up to about percent hydroxylare useful as plasticizers and as control agents for manufacture offoamed plastics. The oligosaccharide propionates can be prepared bydegrading a cellulose propionate in the presence of an acid catalyst.

This invention relates to low viscosity cellulose esters and theirincorporation as additives in plastic materials.

More particularly, this invention refers to cellulose prothe degradationof cellulose esters into low-viscosity oligosaccharide esters.

We have found that both oligosaccharide triesters (fully esterifiedoligosaccharide units) and partially hydrolyzed oligosaccharide esters(partially esterified oligosaccharide units) may be used as plasticizersin commercial plastic materials. When so used, they provide improvedflow of the plastic and have superior ability to remain in the plasticeven when exposed to moisture or prolonged high temperature.

We have also found that oligosaccharide esters provide a means ofcontrol over the foam structure of polymeric foam products, such aspolyurethane foams. When foamed plastics are made, it is important thatthe desired foam structure exists as the plastic sets. For example,polyurethane plastics, which are the reaction products of organicpolyisocyanates and polyhydroxyl compounds, may be foamed by theaddition of water and catalyst to generate CO gas; or, inert gas may beintroduced in the prepolymer system from without. If the prepolymersolution is not sufliciently viscous, the entrapped gas will escape andi the foam will collapse before the plastic solidifies. If the viscosityof the prepolymer solution is too high, the addition and thorough mixingof additives into the prepolymer solution is diflicult and the plasticmay set before an adequate foam structure is established. With theaddition of oligosaccharide esters the viscosity of the prepolymer mixcan be controlled prior to foaming. When the viscosity of the prepolymersolution is increased by the addition of from about 0.5 to about 5Weight percent of the oligosaccharide ester (based on the weight of thereaction products), the bulk density of the foam becomes less becausemore of the gas is retained. A more uniform cellular structure results,showing less tendency to shrink or collapse when cured.

In the following examples, all parts are by weight unless otherwisespecified.

3,518,249 Patented June 30, 1970 PREPARATION OF OLIGOSACCHARIDE TRIPROPIONATE The oligosaccharide tripropionate was prepared by degradingcellulose tripropionate in the presence of methanesulfonic acid orperchloric acid catalyst. The following examples will serve to enableone skilled in the art to manufacture and isolate oligosaccharidetriesters of low intrinsic viscosity.

Example 1 The starting material consisted of cellulose tripropionate.Its analysis was as follows:

Inherent viscosity {1;} (acetone) 0.76 Percent 'OH 0.04 Percent totalsulfur 0.0023 Melting point (M.P.) C. 239 Char point (C.P.) C. 260

METHANESULFONIC ACID DEGRADATION 200 parts of cellulose tripropionatewere dissolved in 90 parts of propionic anhydride and 360 parts ofpropionic acid at C. The catalyst, consisting of 24 partsmethanesulfonic acid in 50 parts of propionic acid was slowly added tothe solution. The solution was stirred rapidly for approximately 15minutes and was held in the 80 C. bath for 23 hours without furtheragitation, then the product was precipitated and washed in distilledwater. Prior to the final wash, a 5% sodium bicarbonate solution wasslowly added to the product until the slurry became neutral. The productwas given a final wash with distilled water and dried in a 50 C. Theproduct had the following properties:

{1;} at 0.25 g./10O cc. acetone 0.02 M.P. C 8085 C.P. C. 270 Percenttotal sulfur 0.001

PERCHLORIC ACID DEGRADATION A conventional glass-lined reactor heated to80 C. was charged with 1800 parts of propionic anhydride and 7200 partsof prionic acid, to which were added 4000 parts of cellulosetriproprionate starting material. Upon complete solution of thetripropionate, the catalyst, consisting of 5 parts of perchloric acid in1000 parts of propionic acid,

was added slowly with stirring. After 23 hours, the prodnot had thefollowing properties:

{1 at 0.25 g./l00 cc. acetone 0.03 M.P. C. 53-65 C.P. C 295 Percenttotal sulfur 0.003

Hydrolyzed oligosacchoride propionates were prepared in the followingmanner from the oligosaccharide tripropionates.

Example 2 {1 acetone (0.25%) 0.01 M.P. C. 94.0 CF. C. 288.0 Percenttotal sulfur 0.013 Percent OH 1.12

Other suitable methods may be employed to prepare hydrolyzedoligosaccharide propionate, such as, for instance, perchloric acidcatalyzed hydrolysis. Also, a greater degree of hydrolysis may beobtained by allowing the hydrolysis reaction to proceed for a longerperiod of Thus, the oligosaccharide propionates of the present inventioncan contain an average of from about 4 to about 20 anhydroglucose unitsper molecule, but preferably contain an average of from about 4 to about15 units per molecule.

time. Products having as much as of hydroxyl have 5 OLIGOSACCHARIDEPROPIONATES AND been found to have the valuable utility set forth above.TRIPROPIONATES AS PLASTICIZERS However (Preferred products are thosehavmg at most The oligosaccharides were stabilized before being usedabgut 35/2 gydroxyL d f t f 1 as plasticizers in commercial plastic.Stabilization of the ecallse 9 ymers are compose o P 6 0oligosaccharides was carried out in the following manner. cules wlth.dlfierent degrees of polymenzatlon 18 4 parts of potassium acid oxalatedissolved in 250 parts to groups of molecules Over whlch f l Water wasadded to 3000 parts of the dry oligosaccharide trons in properties aresmall before an accurate defillltlOIi propionate with constant stirringThe ester was cooled of the polymer may In order to more pmcle1y withDry Ice and a cold solution of 3 parts p-t-butyldefine theohgosapchandes produce? parts phenol and 1 part of strontium naphthenate(SN) in 30 saccharide tripropionate of intermediate 1nherentv1scos1typarts isopropanol were stirred in The ester was dried (0.11 in acetone)were fractionated into small fractions, overnight under vacuum e.ach 9 9t the ongmal matetlal Frac' Five 20,000 pound samples of commercialcellulose tlqnal preclpitatlpn was earned out from a sqhmon acetatebutyrate were stabilized by adding to each sample oligosaccharide 1n1000 parts of acetone, with precrpita- 20 the following. tion by meansof an acetone-water solution (50:50 by H volume) containing sodiumchloride 2 pounds SN stabihzer, 100 Dissolved in 1000 pounds As can beseen from Table I, the fifth fraction pro- Pounds P- y pi P P f duced anoily liquid of a very low molecular weight. Pounds Potassium acldDlssolved III 500 P Analysis of this oily fraction yielded a molecularweight Oxalaw Water- Of indicating an oligosacchafide tl'ipfopionate 0f2 To each of four of the five stabilized samples above anhydroglucoseunits. The solid fractions (1-4), therewas added a quantity ofplasticizer as listed in the followfore, were all greater than 2anhydroglucose units in ing Table III:

TABLE III 200 parts samples of stabilized cellulose Amount acetatebutyrate Ilastlcizer (parts) Method of addition A-l Oligosaccharidetripropionate (stabilized) 40 Added as a dry powder and tumbledovernight. A-2 Partially hydrolyzed oligosaccharide propionate(stabilized) 40 Do. B Sucrose acetate isobutyrate (SAIB) 40 Dissolved in50 parts isopropanol and stirred into the cellulose acetate butyrate. CDlbntyl sebacatc 40 Do. D None (mAcetone, 0.04; M.P., 86 (1.; C.P., 2950.; percent (1 )Acetone, 0.01; M.P., 94 0.; C.P., 288 (3.; percent totalsulfur, 0.003. total sulfur, 0.013 percent 0H, 1.12.

length, and were probably within the range of 6 to 20 The plasticizedmixtures were dried at 50 C. for 15 units. hours and then compounded on170 C. rolls. TABLE I.FRACTIONATION 0F CELLULOSE TRIPRO- Sheets f each fwere Prepared of equal thlclmess PIQNATE by employing 30 mil ShlmS atthe corners of the stainless g fgfggl iffl -i22323:" steel pressingplates. These sheets were used to determine W i ht I M It t I h '5plasticizer permanence under conditions of prolonged dry 0 e ill o1n 1'1eren 1 Fraction fraction gi ams) g I() C.) cosity (acetone) heat andWater Submerslon' ag-l TABLE IV.PLASTIOIZER RETENTION IN MOLDED SHEETS4. 5 Oily liquid Fractional precipitation of a hydrolyzedoligosaccharide propionate of inherent viscosity (acetone) of 0.13 andOH content of 1.81% also indicated a polymer chain length from about 6to 20 anhydroglucose units.

TABLE IL-FRACTIONAL PRECIPITATION OF HYDRO- LYZED OLIGOSACCHARIDEPROPIONATE Inherent Viscos- Fraction No. Weight (grams) ity (acetone)Percent OH Oily Liquid The unusually low degree of polymerization (DP)of the oligosaccharide tripropionate material was also confirmed bycalculating the DP from molecular weight determinations (measured inbenzene) of 2 low viscosity samples. An oligosaccharide tripropionatewith {1 }=.05 (M.P. 120125 C.) yielded an average DP of about 8, and onewith {1 }=0.02 (M.P. 80-85 C.) had an average DP of about 4.

Besides having good permanence in the molded plastic sheets, theoligosaccharides improved the flow properties of the cellulose acetatebutyrate material. Samples were pressed between two stainless steelplates for 3 minutes at 177 C. under 500 pounds of pressure, with thefollowing results:

TABLE VI.FLOW COMPARISONS Dimensions of Pancake formed OLIGOSACCHARIDEPROPIONATES AS FOAM ADDITIVES Polyurethane foams were prepared bycombining a polyhydroxy compound and tolylene-2,4-diisocyanate atvarious ratios and reaction conditions. The polyhydroxy alcoholsincluded such compounds as diethylene and triethylene glycols, castoroil and the Carbowaxes 400, 600, 1500 and 4000. It was observed thatgood foams were prepared by first obtaining a correct viscosity in theprepolymer stage. To obtain this desired viscosity, partially hydrolyzedoligosaccharide propionates were added which varied in inherentviscosity from 0.01 to 1.0 and in hydroxyl content from 0.8% to 8.0%.The oligosaccharide propionates were dissolved in the polyhydroxyconstituent or the diisocyanate in case of insolubility in thepolyalcohol. With the prepolymer at the desired viscosity, foaming wasaccomplished by rapidly stirring in water and catalyst, therebyproducing CO gas. Several examples are as follows.

EXAMPLE 3 Two parts of an oligosaccharide propionate (I.V. acetone 0.12,OH 3.07%, M.P. 167 C.) were dissolved in 18 parts of Carbowax 400 withheating. Upon cooling, 20 parts of tolylene-2,4-diisocyanate were added,resulting in an exothermic reaction. The reaction proceeded withoutexternal heating and could be foamed in approximately one hour. When thereaction was essentially complete and the mixture had cooled, a catalystof 0.3 part triethyl amine in 2 parts of water was added with rapidstirring. The resultant foam was quite tough, had an even cellularstructure, and showed a minimum of shrinkage on aging.

When this reaction was carried out without the addition of theoligosaccharide propionate, it was necessary to heat the mixture forseveral hours at 120 C. before sufiicient foam viscosity was produced.The correct reaction mixture viscosity was extremely difficult toachieve or reproduce since it had to be cooled in a brine bath beforethe addition of water and catalyst due to an extremely exothermicreaction. At best, the resulting foams were of high density and shrankupon standing over a period of several days.

EXAMPLE 4 To 14 parts' of tolylene-2,4-diisocyanate were added 2 partsof oligosaccharide propionate (I.V. acetone 0.02, OH 2.3%, M.P. 104 C.)with heating. Eighteen parts of castor oil were next added and themixture placed in a C. oven for one hour. Upon cooling 3 parts oftolylene-2,4-diisocyanate were added followed by 0.5 part of triethylamine in 2 parts water, with stirring.

With the addition of the oligosaccharide to the castor oil base foam,the amount of foam shrinkage was lessened and foam rigidity increased.

EXAMPLE 5 Three parts of an oligosaccharide propionate (I.V. 0.02, OH2.3%, M.P. 104 C.) were dissolved in 12 parts triethylene glycol withheating. The solution was cooled in a brine bath and 20 parts oftolylene-2,4-diisocyanate were added with stirring. When sufiicientviscosity had been attained, a catalyst of 0.4 part triethyl amine in 2parts water was rapidly added. The resultant foam was a very large, evencelled foam which did not shrink. Foams without the oligosaccharideadditive became limp and shrank into a tacky mass upon standing forseveral days.

What is claimed is:

1. An oligosaccharide propionate having an average degree ofpolymerization of from about 4 to about 20, and containing at most about10% hydroxyl.

2. An oligosaccharide propionate having an average degree ofpolymerization between about 4 to about 15 and containing from 03.5%hydroxyl.

References Cited UNITED STATES PATENTS 3,057,743 10/1962 Touey et a1106-169 3,030,356 4/1962 Touey et al 260-234 2,931,802 4/1960 Touey etal 260-234 3,386,932 6/1968 Steinmann 260230 DONALD E. CZAJA, PrimaryExaminer R. W. GRIFFIN, Assistant Examiner US. Cl. X.R.

